Lubricating oil



Patented Feb. 13, 1 951 TED PATENT OFFICE fiIiUBRICATIN G OIL John "Mann 'Butler, Dayton, Ohio, (assignor Lto Monsanto Chemical Company, .St.-.L'ouis, -.Mo., "a corporation ofiDelaware :.'No;.Drawing. Application october' 23, 1948, Serial No. 56.267

.rmethod of:altering the: crystallization character- :istics of the paraffin wax dissolved in lubricating oils, and :avoiding the solidification of the lubricant upon cooling.

Many of the commercially available petroleum stocks contain high molecular weight hydrocarbon vwaxes,""and the lubrica-tingoil fractions-separated by various refining procedures, contain a substantial proportion dissolved'therein. Upon coolin'g-theselub'ricantsthe dissolved waxescerys- 'tallize' in sueh form that the ma ss'is -fs'olidifi'ed.

It is known that some substances afiect thewrystallization of the wax and permit the lubricants to retain their fluidity after cooling to temperatures below the normal pour points of the oils.

The purpose of this invention is to provide a convenient and readily available agent for depressing the pour points of lubricating oils. A further purpose of this invention is to enable the selection of an effective pour point depressant for a wide variety of wax containing lubricating oils.

The pour points of lubricating oils are measured by a standard A. S. T. M. procedure, by which a sample of oil is heated and then gradually cooled while observing the fluid characteristics of the sample at every 5 F. interval, the temperature being multiples of 5 F. The pour point is the lowest recorded temperature at which the sample is fluid. The details of the method of determining pour points are set forth in the American Society for Testing Materials Publication, A. S. T. M. Standards on Petroleum Products and Lubricants (1946), p. 93, A. S. T. M. designation: D-97-39'.

It has now been discovered that there is a critical relationship between the length of the carboxylic acid group of allyl carboxylates and the pour point of a wax containing oil in which a polymer of the allyl carboxylate is an effective pour point depressant. Polymers of the allyl carboxylates, having alkyl chains longer or shorter than the critical length, may be less effective, or entirely ineffective in depressing the pour points of the same oil.

In accordance with the invention the polymers of allyl myristate are used as pour point depressants for wax containing oils having pour points between 30 F. and 65 F. Other polymeric allyl carboxylates are not efiective pour point depressants for 30 F. to 65 F. pour oils, and polyallyl z myristate is not effective in higher: or-lowerrpour oils.

In the practice of 'this'invention the polyallyl myristate is prepared by the' polymer-ization of auyi: myris'tate by. heating in the presence 'of peroxy catalysts, such'as benzoyl peroxide. Ihe:.'effectiveness of the polymer asa pour point-de- 'pressant 1 is not materially affected by -'-the molecular weight o'f the polymer; the wide range= of molecular weightsachieved 'by conventionaLpolymerization operations allappearto have thezsame or very similarpounpoint depression. The polymerized allyl myristate. may be used in an amount varying frombi'Ol to' 5. percent byweight, but the preferred operation involvesthe useof from 0.05 to 2 percent. Thegpolymer is dissolved or dispersed in the lubricating oil by adding it directly or stirring sthesmixturexuntil a homogeneous mixture or solutionisefiected. ltisirequently desirable to prepare master batches by dispersing or dissolving large amounts of the polyallyl myristate in a lubricating stock, and thereafter mixing the concentrate with a suitable larger quantity of untreated oil, the proportions being achieved so as to have a small but effective proportion of the polyallyl myristate in the final lubricant.

This invention may be practiced by using mixtures of polymeric allyl carboxylates containing predominantly polymeric allyl myristate, and copolymers of mixed allyl carboxylates containing predominantly allyl myristate and substantial proportions of near homologues, for example allyl caprate, allyl laurate and allyl palmitate. These copolymers are generally derived from the allyl esters of the mixed fatty acids as obtained from animal and vegetable oils by saponification.

The pour point depressants described in this specification may be used in combination with other known depressants and with other modifying agents, such as viscosity index improvers, anti-oxidants and detergents.

The critical characteristics of the pour point depression of lubricating oils with polyallyl myristate are demonstrated by the following specific examples.

Example 1 The critical efiect of the length of the carboxylate chain of various polymerized allyl carboxylates was demonstrated by preparing one percent by weight of polymerized allyl laurate, polymerized myristate, polymerized allyl palmitate and polymerized allyl stearate in a wax containing lubricating oil having a 45 F. pour point.

3 The four samples were tested by means of the standard A. S. T. M. measuring method and the observed data is set forth in the following table.

Pour Depres- Polymer of Point, sion, F. F.

Allyl Laurate 45 Allyl Myn'state 35 Allyl Palmitate 25 I 20 Allyl Stearate 60 Example 2 The critical effect of the original pour point of the oil upon the degree of pour point depression achieved was effectively demonstrated by dissolving one percent by weight of polyallyl myristate in samples of oil having 20, 45 and 60 F. pour points. The following table sets forth the original and final pour points of the oils tested as well as the pour point depression achieved.

Original 53 Depres- Pour Point, Point S1011, r F. g a F F.

This table of measurements demonstrates that polyallyl myristate has no pour point depression action in 20 pour oil, but that it has an efiective pour point depression action in and F. pour oils. ,The polyallyl myristate also has a pour point depression effect on oils having pour points in excess of 60 F., for example F. pour oils, but these are'of little commercial importance. Effective pour points depressions of 30 F. pour oils are also achieved by using polyallyl myristate.

The invention is defined by the following claim.

I claim:

A lubricating composition which comprises a paraffin wax containing hydrocarbon lubricating oil having a pour point of 30 to 65 F., containing intimately dispersed therein from 0.05 to 2 percent by weight of polyallyl myristate.

JOHN MANN BUTLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS by Kalichevsky, Reinhold Publishing Co., 1938, page 183. 

